Attempts have been made to provide powdered compositions suitable for mixing with milk or water for the manufacture of non-gelled acidified, milk-product drinks. For example, U.S. Pat. No. 4,530,850 (Jul. 23, 1985) provided a powdered composition that, upon mixing with milk, formed a non-gelled, acidified, milk-product drink without curdling of the milk proteins. The powdered composition contained about 1 to about 9 percent of an edible acid, about 0.5 to about 1.9 percent of an instant cold-water soluble gelatin, about 1 to about 10 percent of an edible natural or modified polysaccharide gum, about 20 to about 90 percent sweetening agents, and an effective amount of flavoring and coloring agents. The beverage was prepared by vigorously mixing (e.g., in a blender at high speed for 10 seconds or in a shaker for an unlisted time) the powdered composition into milk. It was reported that the gelatin included in the powder became attached to the casein in the milk, thereby stabilizing the milk proteins at lower pH; the gum was reportedly used to improve the viscosity and texture of the final beverage product. Attempts to prepare the beverage of U.S. Pat. No. 4,530,850 without vigorous mixing (i.e., gently mixing with a spoon) by the present inventors were generally unsuccessful.
U.S. patent application Ser. No. 11/958,490, owned by the same assignee of the present invention, provided instant acidified milk beverages and methods for producing such instant acidified milk beverages. It also provided a powdered composition which can be added to a milk product with minimal mixing to produce an instant acidified milk beverage having a smooth texture. The powdered composition generally contained sugar, citric acid, a buffering or bite reducing agent, guar gum, artificial sweeteners, a calcium fortification agent, emulsifiers, and optional flavorings and colorants. Typically, the powdered composition disclosed in U.S. patent application Ser. No. 11/958,490 was combined with pasteurized liquid milk to provide the desired beverage. Most of the milk produced in Brazil is pasteurized using the ultra high temperature (“UHT”) method (i.e., typically 130° C. to 138° C. for two to four seconds). Thus, the inventors used only UHT pasteurized milk in developing their invention. It was assumed that this invention would work with milk independent of the pasteurization method used.
It has now been determined that when the powdered composition disclosed in U.S. patent application Ser. No. 11/958,490 is combined with liquid milk pasteurized using the high temperature short time method (“HTST”), the milk frequently curdles. Since most milk produced in the United States is pasteurized using the HTST pasteurization method (typically at 71.5° C. for 15 seconds), the invention described in U.S. patent application Ser. No. 11/958,490 has limited usefulness in the United States (or other locations where HTST pasteurization methods are used). The present invention overcomes this limitation of the co-owned invention because it provides a way of acidifying HTST milk products without producing any curds.